Burglar-alarm



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, gaged with pinion e.

UNITED STATES JOSEPH V. KNIGHT, OF

PATENT OFFICE.-

LYNN, MASSACHUSETTS.

SPECIFICATION forming part of Letters Patent No. 256,145, dated April11, 1882,

` Application filed January 524, 1882. (No model.)

To all whom it may concern:

Be it known that I, JOS. V. KNIGHT, of Lynn, county of Essex, andCommonwealth of Massachusetts, have invented certain new and usefulImprovements in Burglar-Alarms; and I do hereby declarethat thefollowingis a full, clear, and exact description of the same.

The object of this invention is to obtain a simple, cheap, and reliableautomatic alarmbell for use in stores, offices, and houses, forapplication to doors, shutters, and other swin ging devices in suchmanner that when the door or shutter, as the case may be, is opened themovingof the same will release a hammer and cause the bell to sound andgive the desired alarm. f

The invention consists in matters of construction hereinafter fullydescribed and claimed.

In the accompanying drawings, Figure l shows a side elevation ot'myimproved burglaralarm. Fig. 2 is the same as Fig. l with theface-plate removed to show the inside mechanism. Fig. 3 shows the alarmin combination with a door.

The case A is provided with three cross-bars, B, O, and D,designed tosupport the operative mechanism. The pinion e is pivoted to thecross-bari), and is revolved by the cross-sprin g d, arranged about itsaxle, as shown in Fig. 2. Said pinion eengageswith and turnsthe smallerpinion a, thereby giving motion to the escapewheelf,whieh in'turnoperates the escapement h so as to reciprocate the hammer fn. and soundthe bell E, all in an obvious manner. A pawl has its end pivoted to theear 2 and engages with the pinion e, so as to lock the pinion whendesired, as referred to hereinafter. The lever-ratchet 3 is centrallypivoted to the cross-bar O. Said ratchet engages at one end with thepinion e and at its opposite end with the button 4, and is disengagedfrom the pinion e by operation of the spring 5. Fig. 2 shows themechanism set ready foran alarm, in which condition the ratchet 3appears en-V The spring 5, being depressed by the ratchet, is preventedfrom acting so long as the end of the ratchet is held down by the button4.

The parts are protected from dust or injury by a face-plate, which isperforated, as shown in Fig. l, being thereby better-adapted to thetransmission of sou'nd.

The alarm is. attached to the door or other swing device by screws, asshown in Fig. 3. It is set for operation through suitable holes, 6, 7,and 8, made in plate H. By reason of a key fitted in an obvious mannerthe spring d is first wound up. lhe ratchet 3 is then depressed till itsinner end engages with the pinion c, whereupon the door is closed withthe outer end of the ratchet 3 under the button 4. It will now be'understood that should the door be opened sufficiently to move the endof ratchet operate to release the pinion e, and the alarm would begiven. i

It' it is desired to open the door without giving an alarm, it is onlynecessary to insert the key in hole 6 and throw the ratchet intoengagement with the pinion e, whereupon the door may be opened,andalthoughA the ratchet 3 is disengaged from the pinion c,'tl1e pinion isstill locked bythe ratchet 1, so that no alarm will be sounded.

From the foregoing it will appear that by this my invention I am enabledto make a compact, simple, and reliable alarm-bell suitable forapplication to doors or other swinging devices where it is desired thatan alarm should be given upon the opening of the Same.

Having thus described my invention, what I claim is 1. In aburglaralarm, the combination of a clock-spring, gearing e af, anescapement, h, a hammer, and a bell with a pivoted springpawl, 3, and astop or button, 4, all constructed and adapted to be operatedsubstantially as described.

the pinion e, the spring, gearing c af, escapement h, hammer, and bellwith the Spring-pawl 3, the button 4, and the locking-pawl 1,substantially as described.

In testimony whereof I have signed this specifieationin presence of twowitnesses.

JOS. V. KNIGHT.

Witnesses: l

C. V. TUTTLE,

R. M. JOHNSON.

3 away from the button 4 the spring 5 would 2. In a burglar-alarm, thecombination of 9o

